^ I don't see a resistivity vs. temperature plot anywhere in the original paper (as it is customary in these kinds of articles), probably because this is a surface effect and the graphite particle won't be able to sustain superconducting behaviour long enough to take the measurement. Still a good progress though. I find the recipe rather amusing, wonder what the referees said about it...

It looks like they're inferring superconductivity via the magnetic moment. I don't know a whole lot about superconductivity but the article did mention a change in the magnetic moment being linked to superconductivity.